Coupled rangefinder / parallax 4x5 camera

ABSTRACT

A different size format camera utilizing the body shell of a 3¼×4¼ format camera and an adaptor that changes a 3¼×4¼ format photographic system to a different size film format. In particular, a coupled rangefinder/parallax camera that utilizes components from Polaroid Models  110, 110 A,  110 B,  120, 900  and  150  cameras and the adaptor.

This is a continuation of pending U.S. patent application Ser. No.10/457,339, filed on Jun. 9, 2003, which is a divisional application ofU.S. patent application Ser. No. 10/095,634, filed on Mar. 11, 2002, andissued as U.S. Pat. No. 6,608,971, which claims the benefit of U.S.Provisional Application No. 60/274,987, filed Mar. 12, 2001.

FIELD OF THE INVENTION

The invention relates to an interface for changing the film format ofcameras and the modification of a 3¼″×4¼″ format camera into a 4″×5″format camera utilizing such interface. In particular, the interface isa modification of a Polaroid CB 103 film magazine, which is designed for3¼″×4¼″ film format, to accept films in the 4″×5″ film format.

BACKGROUND OF THE INVENTION

Different film formats exist for still photography to accommodate theneeds and demands in the art of still photography. The most common smallfilm format is the 35 mm used in common point and shoot camera. Themedium film format is between 35 mm and 6 cm in height, which includes 6cm×9 cm and 3¼″×4¼″, which is commonly referred to as 3¼×4¼. The largefilm format is greater than 6 cm in height, which includes 4″×5″,commonly referred to as 4×5, and 8″×10″, commonly referred to as 8×10.

Larger film sizes provide better quality and more detail images. Thelargest practical format for a production hand held camera is the 4×5format because of the limitation on the portability and maneuverabilityof the camera. An 8×10 format camera is heavy and cannot be used as ahand held camera.

All 4×5 camera in the marketplace have either a double windowrangefinder that has one viewfinder window for framing the photographand one rangefinder window for focusing or only has a rangefinderwithout parallax. Single window rangefinder/coupled rangefinder parallaxcombination camera exists for the 3¼×4¼ format, but not for the 4×5format because of the tighter tolerances required for the 4×5 formatcamera and the need for highly skilled workers in the manufacturingprocess, making it economically impractical to manufacture. A coupledrangefinder/parallax combination camera provides the focusing system andcrop lines which permit accurate composition via the rangefinder, i.e.can adjust the crop lines in the viewfinder when adjusting the focus onthe subject to take a picture. Therefore, it is easier to adjustrangefinder and cropping frame because it uses only a single windowrangefinder that includes both the parallax and the rangefinder.

Therefore, there is a need for a lightweight 4×5 camera having a singlewindow rangefinder/coupled rangefinder parallax combination.

SUMMARY OF THE INVENTION

The invention provides an interface and single window rangefinder 4×5camera by converting existing products designed for the 3¼×4¼ format.

One aspect of the invention is the modification of a film magazineprocessing back designed for the 3¼×4¼ format produced by PolaroidCorporation of Cambridge, Mass., called the Model CB 103 camera back forpack films, into a CB 103 interface that may be adapted to acceptdifferent format films, including the 4×5 format.

Another aspect of the invention is the modification/combination ofPolaroid's cameras that accept series 40 roll film (which is out ofproduction and was in the 3¼×4¼ format) and did not allow the use ofconventional wet film holder, such as Model110/110A/110B/120/900/150/160/800, to a single window rangefinder 4×5camera with the CB 103 interface.

A further aspect of the invention is the necessary improvements of themodified Polaroid Models 110/110A/110B/120/900/150/160/800 camera toallow it to become an operable coupled parallax/rangefinder 4×5 camera.

The CB 103 interface of the present invention comprises a frame thatacts as a spacer for interconnecting two photographic components, suchas a 4×5 format film and a camera that accepts the 3¼×4¼ format filmmagazine.

The single window rangefinder 4×5 camera of the present inventionmodifies the Polaroid Models 110/110A/110B/120/900/150/160/800 cameraand utilizes the CB-103 interface to convert a 3¼×4¼ camera into a 4×5camera with a coupled rangefinder/parallax combination that allowssequence shots taken at a higher speed than ever before possible for a4×5 format, at about 1 shot/sec, and allows increased concentration onartistic aspect of picture taking and the ability to capture snap shotswith spontaneity without asking the subject to wait until the camera isbeing readied. Additionally, the modified single window rangefinder 4×5camera of the present invention provides a proper turn knob focusingsystem for accuracy and improved tolerances for a 4×5 format.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D show different views of a Polaroid Model CB 103 filmmagazine, in the open and closed position, FIG. 1E shows the closinglatch of the Model CB 103 film magazine; and FIGS. 1F and 1G showsdifferent views of the pack film holder of the Model CB 103 filmmagazine.

FIG. 2 is a CB 103 interface modified from a CB 103 film magazine inaccordance with the present invention.

FIGS. 3A-3F show the steps of modifying a CB 103 film magazine into a CB103 interface and then into a 4×5 adaptor in accordance with the presentinvention.

FIGS. 4A and 4B shows two different views of the 4×5 adaptor of thepresent invention.

FIGS. 5A and 5B illustrate the alternate use of a CB 103 film magazineor a 4×5 adaptor of the present invention, respectively, on similarcameras.

FIGS. 6A-6E show the steps of modifying a Polaroid 900 body shell toaccept the CB 103 interface and then the 4×5 adaptor for a coupledrangefinder/parallax 4×5 camera of the present invention.

FIGS. 7A-7D show the modification of the focusing system of a Polaroid900 camera for a coupled rangefinder/parallax 4×5 camera of the presentinvention.

FIGS. 8A-8E show the steps of modifying the focusing system of aPolaroid 900 camera for a coupled rangefinder/parallax 4×5 camera of thepresent invention.

FIGS. 9A-9E show the steps of permanently mounting a 4×5 adaptor to aPolaroid body shell by first installing the bottom half of the CB 103interface and then mounting to it the 4×5 adaptor for a coupledrangefinder/parallax 4×5 camera of the present invention.

FIG. 10 shows the different components for the coupledrangefinder/parallax 4×5 camera of the present invention.

FIGS. 11A and 11B show two different combinations of the coupledrangefinder/parallax 4×5 cameras of the present invention, utilizingdifferent components.

FIGS. 12A-12B shows focusing system before modification; FIGS. 12C-Jshow the steps of modifying the focusing system of the coupledrangefinder/parallax 4×5 cameras of the present invention

FIG. 13 shows the additional features of a front tilt and a cablerelease port for the coupled rangefinder/parallax 4×5 cameras of thepresent invention.

FIGS. 14A-14F shows the additional feature of providing a differentshutter size and allowing close up work for the coupledrangefinder/parallax 4×5 cameras of the present invention.

FIG. 15 shows an improved coupled rangefinder/parallax of the presentinvention.

FIGS. 16A-16H show the components and improvement made to the secondarypivoting mirror assembly.

FIGS. 17A-17B show an alternate improvement made to the secondarypivoting mirror assembly.

FIG. 18 shows the components of the coupled rangefinder/parallax 4×5camera of the present invention.

FIG. 19 shows an improved pivoting cam for the coupledrangefinder/parallax 4×5 camera of the present invention.

FIG. 20 shows different views of the completed coupledrangefinder/parallax 4×5 camera of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

CB 103 Interface

With reference to the drawing wherein the same reference numberillustrates the same element throughout, FIGS. 1A-1D show a Polaroid CB103 film magazine 1 for the 3¼×4¼ format pack film, which is to bemodified to become a CB 103 interface 10. FIGS. 1A and 1B show the frontand rear, respectively, of the CB 103 film magazine 1 in the closedposition and FIGS. 1C and 1D show the front and rear, respectively, ofthe CB 103 film magazine 1 in the open position. The CB 103 filmmagazine 1 has a frame 2, which is pivotally connected to a rear door 4on one end and to a closing latch 6 on the opposite end. FIG. 1E showsthe closing latch 6 separated from the frame 2. As shown in FIGS. 1A and1B, the rear door 4 rests on the frame 2 with the closing latch 6latching over the rear door to keep the CB 103 film magazine 1 in theclosed position. Mounted on the frame 2 at the pivoting point betweenthe frame 2 and rear door 4 is a pack film holder 8. As shown in FIGS.1F and 1G, pack film holder 8 has a pressure spring 12 for retaining apack film (not shown), which is inserted into the pack film holder 8when the CB 103 film magazine 1 is in the open position as shown in FIG.1C. Upon closing the CB 103 film magazine 1, the pack film (not shown)rest against another pressure spring 14 mounted on the rear door 4. Alsomounted on the rear door 4 adjacent the end opposite from the frame 2 isa pair of film development rollers 16. When in use, after photographingan image on a pack film, a photograph exits the CB 103 film magazine 1through the film development rollers 16 and an exiting slot (not shown)on the side of the rear door 4.

The modification of the CB 103 film magazine 1 shown in FIGS. 1A-1D, toa CB 103 interface 10, as shown in FIG. 2, requires the removal of thefilm development rollers 16 and milling an opening 18 in the rear door4. The CB 103 interface 10 interfaces a camera that accepts a CB 103film magazine 1 and another camera back having a different film format,such as a film holder, a film holder receiving apparatus or a 4×5 frame.Additionally, the CB 103 interface 10 acts as a spacer to advantageouslyincrease the distance between the lens and the film plane. The milledopening 18 is preferably centered on the rear door 4 such that when CB103 interface 10 is mounted onto a camera (not shown), the projectedimage will properly travel through the milled opening 18 onto the filmwhile maintaining and respecting the functions of the parallax system ofthe camera with the increased distance between the lens and the filmplane. Depending on the focal distance of the lens and the size of thefilm being used on the camera, the thickness or depth of the CB 103interface 10 may be increased from the distance between the lens and thefilm plane for proper function of the parallax system on the camera andthe proper image size for the specific format film. CB 103 interface 10as shown in FIG. 2 has a milled opening 18 of approximately 4″×5″ foradapting to a 4×5 format. Different sized opening 18 may be milled fordifferent purposes, e.g. 35 mm, 6 cm×9 cm, 5×7, etc.

Although the CB 103 interface 10 of the present invention is describedabove as a modification of the CB 103 film magazine 1, other similarlysized frame with structure similar to the CB 103 interface 10 may beused as such an interface 10. The minimum thickness or depth of theinterface 10 of the present invention is {fraction (3/8)} inch toprovide the minimum increased distance between the lens and the filmplane for proper projection of an image onto the film.

4×5 Adaptor Using CB 103 Interface

FIGS. 3A-3F shows the different steps in modifying a CB 103 filmmagazine 1 into a CB 103 interface 10 and then into a 4×5 adaptor 20.FIG. 3A is similar to FIG. 1B and shows a CB 103 film magazine 1. FIG.3B is similar to FIG. 2 and shows a CB 103 interface 10. Although a CB103 interface 10 is described herein for the 4×5 adaptor 20, othersimilarly sized and structured interface 10 may be used. FIG. 3C shows astandard 4×5 connecting frame 15, Horseman Model No. 23707, manufacturedby Komamura Photographic Co., Ltd., which is a Graflock back thataccepts regular two sided 4×5 cut film. Other camera backs or 4×5 framesfrom other manufacturers can also be used. As shown in FIG. 3D, the 4×5connecting frame 15 is placed under and adjacent the milled opening 18of the rear door 4 of CB 103 interface 10. A template 22 for properalignment of connecting frame 15 and CB 103 interface 10 is used. Theconnecting frame 15 is connected to the CB 103 interface 10 with four(4) screws 24 with black RTV silicone seal therebetween to trap light.As shown in FIG. 3E, two strips of syntra light traps 26 are used tocompensate the difference in size on the sides of the CB103 interface 10(118.2 mm) and the outer dimension of the smaller side of the 4×5connecting frame 15 (140 mm). Each of the light trap 26 measures 10.7 mmand are secured on each side of the CB 103 interface 10 and on theconnecting frame 15 with a bonding material such as cyanoacrylate andscrews 24. Black RTV silicone seal is also used when light traps 26 aremounted on the connecting frame 15. FIG. 3F shows the completed CB 103interface for a 4×5 format 20, herein after referred to as 4×5 adaptor20, viewed from the side of the mounting frame 15. FIG. 4A shows the 4×5adaptor 20 viewed from the side of the CB 103 interface 10, which isopposite of FIG. 3F. FIG. 4B shows the side view of the 4×5 adaptor 20and the interconnection of the CB 103 interface 10 and connecting frame15 and the position of the light trap 26. The distance between the lensand the film plane is increased; in this particular instance, increasedby a total of approximately 36 mm from the original film plane due tothe thickness/depth of the CB 103 interface 10 (25.45 mm) and theconnecting frame 15 (10.4 mm).

The 4×5 adaptor 20 allows the temporary conversion of existingphotographic systems which utilize CB 103 film magazine 1 in the 3¼×4¼format to the 4×5 format, by attaching the 4×5 adaptor 20 to the camerainstead of a CB 103 film magazine rear door 4 as shown in FIG. 1Dwithout permanently affecting the camera. FIGS. 5A and 5B illustrate anexample of a Polaroid CU-5 camera 25 using a CB 103 film magazine 1(FIG. 5A) and a similar Polaroid CU-5 camera 25 using the 4×5 adaptor 20(FIG. 5B). Any 3¼×4¼ format cameras that accept CB103 film magazine 1can be similarly converted to a 4×5 photographic system. Somephotographic system may require adjustment to the focal length when the4×5 adaptor 20 is used. A ground glass panel (not shown) may be mountedonto the connecting frame 15 of the 4×5 adaptor 20 for focusing whenused for close up work. Infinity on cameras with the 4×5 adaptor 20,such as that shown in FIG. 5B, may be achieved with lenses having longerfocal length. Conversion of the CB 103 interface 10 into differentformats other than 4×5, such as 35 mm, 6 cm×9 cm, 5×7, can be similarlyachieved with the steps discussed above.

Converting a 3¼×4¼ Camera into a 4×5 Camera with a 4×5 Adaptor

In the preferred embodiment of this invention, Polaroid 110 seriescameras, in particular, Models 110/110A/110B/120/900/150/160/800, arechosen for conversion into 4×5 cameras because they have the basicnecessary parts and an accurate turn knob focusing system. However,additional modification and improved tolerances of such a camera, to bediscussed below, is necessary for a 4×5 format camera.

In comparison with the Polaroid CU-5 camera shown in FIG. 5B, theconversion of the Polaroid 110 series camera is permanent and the 4×5adaptor 20 becomes an integral part of the final product.

The coupled rangefinder/parallax 4×5 camera of the present inventionrequires the following parts, which are considered to be available now,from existing Polaroid Models 110/110A/110B/120/900/150/160/800 cameras:Parts* 110 110A 110B 120 900 150³ Focusing door 65 X X X X X Focusingdoor hinges 54 X X X X  X¹ X Focusing train 55 X X X X X Lens board 50 XX X X Body shell with coupled X X rangefinder/parallax 28 Original lens²X X X X Cams 120 and coupling X X X X X arms 115*Each of the parts from alternate Models listed in the table above areidentical except for the focusing door hinges.¹It is preferable that focusing door hinges 54′ from Model 900 is usedbecause it offers play reduction adjustment, which improves performanceof the final camera.²Other optional lens, with appropriate washermay be used.³The constructions of Models 160 and 800 are identical to Model 150 inall relevant aspects.

As shown in the table above, the only model with all the basic neededparts is Model 110B. However, Model 110B is scarce and costly to obtainand usually in poor condition. Therefore, the body of the amateurversion of Model 110B, Model 900, which also has a coupledrangefinder/parallax assembly, is used, with the remaining partsreplaced from other available models.

FIG. 6A shows the body shell 28 of a Model 900 camera in an openedposition viewed from the front, exposing the inner panel 32 with aroller on the left of the front shell 34 and the back cover 36 on theright of the front shell 34. FIG. 6B shows the body shell 28 in a closedposition, viewed from the bottom, showing the front shell 34 and theback cover 36. The body shell 28 is cut at two locations to accommodatethe 4×5 adaptor 20, which replaces the old roll film back system. Thefirst cut 30 is at an angle, on the left side of the front shell 34, at27.5 mm from the right edge of the original film opening 38 on the backcover 36. The second cut 35 is a ninety degree cut, on the back cover,at 52 mm from the hinge end of the back cover 36. The two sections cutfrom the body shell 28, shown in cross-hatched in FIG. 6A, arediscarded. The measurements for these two cuts is designed for the 4×5adaptor 20, but may vary 1 cm in either direction depending on the sizeof the interface to be used between the body shell 28′ and the 4×5connecting frame 15. As mentioned in the section above for the 4×5Adaptor Using CB 103 Interface, a 3¼×4¼ camera can also be convertedinto different formats other than 4×5, such as 35 mm, 6 cm×9 cm, 5×7,etc. and the two cuts 30 and 35 will be cut accordingly. Further,different sized bellows may be used to correspondingly accommodate alarger or smaller format that the camera is being converted to toprovide sufficient image projection through the bellow to the filmplane. The edges of the first and second cuts 30 and 35 are beveled andrubber edges 42 are installed for protection, shown in FIG. 8D.

FIG. 6C shows the bottom view of the body shell 28′ after the first andsecond cuts 30 and 35. As shown in FIG. 6C, protruding edges 44 arelocated along the top (not shown) and bottom edges of the front shell 34where the back cover 36 originally seals to trap light. The protrudingedges 44 must be milled so that the 4×5 adaptor 20 can be mountedflushed against the body shell 28 and ninety degree to the base of thelens board 50, to be described with FIGS. 12A-12J. FIG. 6D shows thebody shell 28′ without the protruding edges 44. FIG. 6E is the bodyshell 28′ in the open position, view from the back.

FIGS. 7A-7D show the modification of the focusing system 48 of aPolaroid 900 camera 40 for a coupled rangefinder/parallax 4×5 camera.FIG. 7A shows a Polaroid Model 900 camera 40 with a coupledrangefinder/parallax assembly 46. FIG. 7B shows the focusing system 48of the Model 900 camera 40 removed, which is replaced by the focusingsystem 52 from a Polaroid Model 110 series camera (shown in FIG. 7C).FIG. 7D shows the Model 900 camera 40 with the focusing system 52re-hinged onto the camera 40, which description will follow.

FIG. 8B shows the body shell 28′ with the focusing system 48 (FIG. 8A)of a Polaroid 900 camera 40 removed. A pair of focusing door hinges 54are installed onto the body shell 28′. The focusing system 52 from aPolaroid Model 110 series camera (shown in FIG. 8C) is re-hinged ontothe body shell 28′ and the focusing door hinges 54, as shown in FIGS. 8Dand 8E.

FIG. 9A shows the CB 103 interface 10 for permanently installing ontobody shell 28′. FIG. 9B shows that a template 56 is used to drill aplurality of holes through the body shell 28′. Each hole is tapped andthe CB 103 interface 10 is secured to the body shell 28′ with screws 24,as shown in FIG. 9C and black RTV silicone seal is used between the bodyshell 28′ and the CB 103 interface 10 to trap light. The 4×5 adaptor 20modified from the CB 103 interface 10 for the 4×5 format as described inconnection with FIGS. 3A-3F above, is then mounted onto the body shell28′, as shown in FIG. 9D, without the focusing system 52. FIG. 9E showsthe coupled rangefinder/parallax 4×5 camera 45 of the present invention,with the focusing system 52 installed, which is to be described inconnection with FIGS. 12A-12J. FIG. 10 shows a different view of thedifferent components for the coupled rangefinder/parallax 4×5 camera 45.

FIG. 11A is a coupled rangefinder/parallax 4×5 camera 45 using all thecomponents from a Model 110B camera. FIG. 11B is a coupledrangefinder/parallax 4×5 camera 45′ using a body shell 28′ from a Model900 camera with components from other Model 110 series cameras. Thedifference between the cameras 45 and 45′ are the focusing door hinges54 and 54′. As discussed above, focusing door hinges 54′ of the Model900 camera provides play reduction adjustment.

FIGS. 12A-12B show the original focusing system 48 before modification,with unmodified lens board 50, focusing train 55 and original infinitylocking plate 60 in its original position. FIG. 12B shows the positionof the lens board 50 at infinity, with the lens board 50 latched ontothe infinity locking plate 60. The focusing train 55 is slidablyconnected to the focusing door 65 and is controlled via a focusing knob70. FIG. 12C shows the lens board 50 with the base having two roundholes 58, each measuring {fraction (1/8)} inch in diameter. The holes 58must be enlarged to {fraction (7/32)} inch in diameter, by drilling witha #12 drill bit, as shown in FIG. 12D. The enlarged holes 58 are thentapped with a {fraction (1/4)} inch 20 nc taps 62, as shown in FIG. 12E.FIG. 12F shows the focusing train 55 with the infinity locking plate 60removed (as shown in FIG. 12G) with a piece of Velcro strip 64 appliedto the front of the focusing train 55. Velcro strip 64 acts as a tiltbed providing upward friction to support the front bar 66 that joins thelens board arms 68 when the tilt feature is activated (as shown in FIG.13). Strip 64 of a material different than Velcro that providesfrictional resistance may be used. FIG. 12H shows that a template 72 isused for drilling new holes 74 on the focusing train 55 for therepositioning of the modified infinity locking plate 60′. The modifiedinfinity locking plate 60′ (as shown in FIG. 121) requires the removalof the two opposite tips 76 from the original infinity locking plate 60(as shown in FIG. 12G) that extend outwardly to allow the lens board 50′to extend beyond the modified locking plate 60′ in order for thefocusing door 65 to close when closing the camera 45. The modifiedinfinity locking plate 60′ is then secured onto the focusing train 55with a bonding material such as cyanoacrylate and screws 24, as shown inFIG. 12J. With the lens board 50′ locked at the new infinity position,as shown in FIG. 12J, the set screws 24 are tightened until they matchthe holes 74 on the lens board 50′ to prevent unwanted swinging and toensure that the base of the lens board 50′ remaining ninety degree tothe film plane. The bellows that connects the camera body to the lensboard 50′ is of sufficient length to accommodate the full range ofmotion along the focusing train 55.

FIG. 13 shows two new features, the tilt feature and the cable releaseport, of the coupled parallax 4×5 rangefinder camera 45 of the presentinvention. As discussed above, the tilt feature is accomplished byproviding a Velcro strip 64 on the focusing train 55, which allows thefront bar 66 connected to the lens board arms 68 to be frictionally heldin a forward tilt position. A cable release port 78 (shown in FIG. 12J)on the focusing door 55 is provided for a cable release 82.

As shown in FIG. 14A, the original shutter opening 84 on the originallens board 50 is for a #0 shutter. The shutter opening 84 is milled andenlarged for a #1 shutter opening 84′, as shown in FIG. 14B. The shutteropening 84 may be milled to different sizes to accommodate differentoptional lens and their respective washers. The center stop 88 at thebase 86 of the lens board 50 (as shown in FIG. 14B) is eliminated (asshown in FIG. 14A) to allow the lens board 50′ to move beyond therepositioned and modified infinity locking plate 60′ on the focusingtrain 55′ to allow close up capabilities as an optional feature (asshown in FIG. 14C). A second center stop 92 (as shown in FIG. 14D) onthe focusing train 55′ cooperates with the center stop 88 at the base 86of the lens board 50′ to prevent the lens board 50′ from falling offwhen it is receded to close the camera. Because the center stop 88 iseliminated, the center stop 92 is not necessary and is also eliminatedby flattening it, as shown in FIG. 14C. A replacement stop 94 is addedat the end of the focusing train 55′ to prevent the lens board 50′ fromfalling off the focusing train 55′, as shown in FIGS. 14C (top view) and14E (bottom view). The replacement stop 94 may be added to either sideat the end of the focusing train 55′. Furthermore, the replacement stop94 may be a {fraction (4/40)} or {fraction (5/40)} socket head screwinstead of the ledge shown in FIGS. 14C and 14E. FIG. 14F shows theconnection of the lens board arms 68 to the focusing train 55′.

Adjustments/Refinements to the Coupled Rangefinder/Parallax 4×5 Camera

The coupled rangefinder/parallax 4×5 camera 45 of the present inventionrequires additional adjustments or refinements to improve the tolerancesfor the 4×5 format. Larger film format has less depth of field, i.e. canonly focus within a smaller range, and more resolution, i.e. sharpnessof image. A 4×5 format has a depth of field within inches with lens wideopen; whereas, 35 mm format is capable of focusing on two items morethan a few feet apart with the lens wide open. Due to the decrease depthof field and increased resolution, a more precise and accurate focusingsystem is necessary because slight vibration or movement can de-focusthe image or de-calibrate the focusing system. Additionally, due to theage of the cameras, all rangefinder optical parts must be cleanedthoroughly, such as with acetic acid based dilutions, and lubricatedwith oil to prevent further micro-oxidation of gunmetal parts.

FIG. 15 shows an improved coupled rangefinder/parallax 90. The primarymirror 96, i.e. look through mirror, is permanently fixed to therangefinder frame 98 with black or clear RTV silicone to avoidde-calibration by impact. Model 110A/110B/120/900/150 cameras come witha 127 mm lens and when the camera is modified to become a 4×5 format,only ninety percent (90%) of the image area captures by the film iscovered by the original parallax. The original parallax utilizes asingle transparent polycarbonate loupe 102 that is flat on one side andhas a 7.5× power on the other. To increase the coverage of the parallaxto one hundred percent (100%), a second loupe 104 with 7.5× power isstacked on top of the original loupe 102 to create a final loupe thatprovides a 15× power. The second loupe 104 may have different power toprovide accurate coverage for different focal length. Alternatively, anew single loupe with the appropriate total power may be used to replacethe original and second loupes 102 and 104. Alternatively, a lens havinga concave surface and an opposite convex surface (not shown) may bemounted in front of the rangefinder frame 98 with the concave surfaceadjacent the rangefinder frame 98 to provide proper coverage of theparallax.

FIG. 16A shows the secondary mirror assembly 110, with a secondarymirror 106, i.e. pivoting mirror (see also FIG. 16C), retained in amirror frame 108 (see also FIG. 16D) that is held against a pivotingmirror chassis 112 (see also FIG. 16E) by a steel clamp spring 114 (seealso FIG. 16F) and two calibration screws 116A and 116B (see also FIG.16E). FIGS. 16G and 16H show different views of the secondary mirrorassembly 110 of FIG. 16A. The two calibration screws 116A and 116B areat diagonally opposed positions; one for vertical calibration and theother for horizontal calibration. The tolerance of the secondary mirrorassembly 110 is improved by providing a third calibration screw 116C, asshown in FIG. 16B, to the horizontal calibration to preventde-calibration by impact and to improve reliability of focus, which isessential in a 4×5 camera. Once calibration of the pivoting mirrorassembly 110 is accomplished and the rangefinder is verified to beaccurate, the third calibration screw 116C is then secured with abonding material such as cyanoacrylate.

An alternative improvement of the secondary mirror assembly 110 is shownin FIGS. 17A-17B. The clamp spring 114 compresses and holds thesecondary mirror assembly 110 together to maintain the calibrations ofthe secondary mirror 106 to accurately align both axes of the verticaland horizontal beams to allow the two images in the rangefinder tosuperimpose when the camera is in focus. Due to the age of the camera,the steel clamp spring 114 as shown in FIG. 16F lost part of its tensilestrength and does not provide accurate tension. Furthermore, not enoughtension is provided in the horizontal calibration while excessivetension is provided in the vertical calibration because of theoff-centered position of the clamp spring 114, as shown in FIG. 16H. Inorder to raise the tension of the horizontal calibration to withstandthe use and application for a 4×5 camera 45 of the present invention,additional tension is provided to the clamp spring 114 by bending it, asshown in FIG. 17A. However, the increased tension to the horizontalcalibration 116B further increases the tension to the verticalcalibration, which fails to stay true because the calibration screw 116Afor the vertical calibration cannot withstand the increase pressured tomaintain its calibration. In order to maintain both the vertical andhorizontal calibrations, a quick setting bonding material is used aftercalibrations. A fast cured bonding material that may be used iscyanoacrylate with the use of an accelerator that speeds the curingperiod from twenty-four (24) hours to within seconds. The cyanocrylatematerial is also harder and stronger with the use of the acceleratorbecause the fast curing period avoids the normal shrink andtransformation due to the varying humidity during the extended curingperiod. The quick setting bonding material is preferably used on bothcalibration screws 116A and 116B and extend to the walls on the pivotingmirror chassis 112, as shown in FIG. 17B, to prevent the calibrationscrews 116A and 116B from de-calibrating.

The coupling focusing arm 115, as shown in FIG. 18, has two movingsections 118 joined by a rivet 122 that acts as an elbow joint. One ofthe moving section 118 is connected to the focusing train 55′, the othermoving section 118 is connected to the pivoting cam (not shown), to bedescribed with FIG. 19. The rivet 122 of the original coupling focusingarm 115 produces displacements/play in the range of 12000^(th) to20000^(th) of an inch movement, which is a catastrophic movement for a4×5 format, resulting in inaccurate focus because the rangefinder wouldnot react correspondingly to the displacement of the lens. Therefore, anew rivet 122′ made of a harder material is necessary to minimizeunwanted displacements or distortion such that true correspondenceexists between what is seen through the viewfinder and what the lenscaptures. Thereby, the reliability of the coupled rangefinder/parallax4×5 camera of the present invention is increased. In the alternative,the original rivet 122 may be crimped to expand its diameter to minimizethe displacements and improve its reliability.

As shown in FIG. 19, the secondary mirror assembly 110 is controlled bya pivoting cam 120 mounted on a stud 124. The coupledrangefinder/parallax assembly includes the coupled rangefinder/parallax90, secondary mirror assembly 110, and pivoting cam 120, which arehoused in a plastic housing. The opposite end of the stud 124 isconnected to the coupling focusing arm 115 (now shown). The originalpivoting cam 120 is set on the stud 124, and therefore, on the couplingfocusing arm 115 by a brass flathead screw (not shown), which did notprovide the necessary torque to effectively secure the pivoting cam 120.Furthermore, the end of the stud 124 where it meets the pivoting cam 120is round and slippery. To improve traction between the stud 124 and thepivoting cam 120, the stud 124 is knurled with a knurling tool such thatthe pivoting cam 120 is held much more effectively. To provide thenecessary torque, the flathead screw is replaced with a new {fraction(2/56)} inch steel allen socket head screw 126. The curvature of thecurved edge 128 of the pivoting cam 120 corresponds to a specific lens.The original camera has a standard notch 132 etched into the cams 120 toindicate the standard position when the lens is focused to infinity.This standard notch 132 is not applicable to the coupledrangefinder/parallax 4×5 camera 45 of the present invention because notwo lenses have identical focal length, which is more critical on a 4×5format than smaller formats and lenses, and lenses are composed ofmultiple elements or each has minute differences in curvature that whencombined to produce an image projected onto a focal plane, thesedifferences from lens to lens requires that the pivoting cam 120 drivesthe rangefinder to have slightly different curvature for each specificlens. Therefore, cams 120 with different curvatures need to be re-cut toprovide for lens with focal lengths of 90 mm, 100 mm, 68 mm, 135 mm and150 mm. For verification of the curvature of the pivoting cam 120 inrelation to a specific lens, focus the rangefinder accurately atminimum, medium and maximum distance to achieve all three focus pointsin coordination with the lens and the curvature of the cam 120 mustreflect a displacement equal to that of the focusing train 55.

FIG. 20 shows different views of the completed coupledrangefinder/parallax 4×5 camera of the present invention.

It is understood that the above described modification of a 3¼×4¼ formatcamera to a 4×5 format camera may be performed on other 3¼×4¼ formatbody shells not having a coupled rangefinder/parallax combination, suchas Models 110A or 120. Additionally, other 3¼×4¼ format camera fromother companies may be similarly converted to a 4×5 format camera.

Although certain features of the invention have been illustrated anddescribed herein, other better modifications and changes will occur tothose skilled in the art. It is, therefore, to be understood that theappended claims are intended to cover all such modification and changesthat fall within the spirit of the invention.

1. A camera comprising: a body shell from a 3¼×4¼ format camera selectedfrom the group consisting of Polaroid Models 110, 110A, 110B, 120, 150,160, 800 and 900 cameras; a coupled rangefinder/parallax assembly from a3¼×4¼ format camera selected from the group consisting of PolaroidModels 110B and 900 cameras on said body shell; means for holding films;and an adaptor between said body shell and said holding means.
 2. Thecamera of claim 1 wherein said holding means comprises a camera back. 3.The camera of claim 1 wherein said holding means comprises a filmholder.
 4. The camera of claim 2 wherein said camera back is a cameraback other than a camera back selected from the group consisting ofPolaroid Models 110, 110A, 110B, 120, 150, 160, 800 and 900 cameras. 5.The camera of claim 2 wherein said camera back is a camera back having aformat other than a 3¼×4¼ format film.
 6. The camera of claim 1 furthercomprising: a coupled rangefinder/parallax housing from a 3¼×4¼ formatcamera selected from the group consisting of Polaroid Models 110B and900 cameras enclosing said couple rangefinder/parallax assembly.
 7. Acamera comprising: a body shell from a 3¼×4¼ format camera selected fromthe group consisting of Polaroid Models 110, 110A, 110B, 120, 150, 160,800 and 900 cameras; a lens and a corresponding washer attached to saidbody shell; means for holding films; and an adaptor between said bodyshell and said holding means.
 8. The camera of claim 7, wherein saidlens is a lens other than a lens selected from the group consisting ofPolaroid Models 110, 110A, 110B, and 120 cameras.
 9. The camera of claim7, wherein said washer is a washer other than a washer selected from thegroup consisting of Polaroid Models 110, 110A, 110B, 120, 150, 160, 800and 900 cameras.
 10. A camera comprising: a body shell from a 3¼×4¼format camera selected from the group consisting of Polaroid Models 110,110A, 110B, 120, 150, 160, 800 and 900 cameras; a focusing doorpivotally mounted to said body shell; a focusing train slidably mountedon said focusing door; a lens board mounted substantially normal to andon said focusing train; a bellows connecting said body shell to saidlens board; means for holding films having a predetermined film format;and an adaptor between said body shell and said holding means.
 11. Thecamera of claim 10 wherein said bellows having a length sufficient toaccommodate a full range of motion on said focusing train.
 12. Thecamera of claim 10 wherein said bellows having a size sufficient forsaid predetermined film format.
 13. A camera having a different sizeformat converted from a 3¼×4¼ format camera comprising: a body shellfrom a 3¼×4¼ format camera selected from the group consisting ofPolaroid Models 110, 110A, 110B, 1120, 150, 800 and 900 cameras having afront shell and a rear shell; an adaptor having opposite sides, whereinone side of said adaptor is adapted to accept the different size formatfilms and the opposite side is mounted to said rear shell.
 14. A cameracomprising: a body shell from a 3¼×4¼ format camera selected from thegroup consisting of Polaroid Models 110, 110A, 110B, 120, 150, 800 and900 cameras; means for holding films; and an adaptor between said bodyshell and said holding means.
 15. The camera of claim 14 wherein saidholding means comprises a camera back.
 16. The camera of claim 14wherein said holding means comprises a film holder.
 17. The camera ofclaim 1 further comprising: a focusing door pivotally mounted to saidbody shell; a focusing train slidably mounted on said focusing door; andmeans for close up capabilities.
 18. The camera of claim 1 furthercomprises means for providing an infinity locking element.
 19. A 4×5camera comprising: a body shell; a coupled rangefinder/parallax assemblyfrom a 3¼×4¼ format camera selected from the group consisting ofPolaroid Models 110B and 900 cameras on said body shell; means forholding films; and an adaptor between said body shell and said holdingmeans.